Light emitting diodes (LEDs) offer exciting benefits in the field of lighting apparatus. There is a strong trend in the industry to replace conventional incandescent light sources with LED units. Among the advantages offered by LED modules is increased flexibility of use. LED modules generally comprise an array of LED units each unit including a reflector (and optionally a refractor) and an LED. The assembly is durable and long-lasting. This arrangement further allows much smaller packages of such light sources which translate into much lower material usage within fixtures containing such sources. Another significant advantage of LEDs is that they yield reliable light with low-power consumption. Further, a solid package of LEDs may be positioned to focus light as might be required.
One of the main hurdles to using LEDs in certain applications is the management of the heat generated by the LED modules. Generally, LEDs themselves create little heat because of their high efficiency as measured by light output per unit power input. There are, however, LEDs that, due to their higher operating currents, may generate considerable more heat than traditional LED modules. Other power-related components within the lighting fixture may also create significant heat. LED performance, and the performance of other power-related components, is directly related to the amount of ambient heat within the housing of a lighting fixture. High levels of heat in a lighting fixture compromise the functionality and life of certain components that are highly susceptible to heat, including LED modules, ballasts, capacitors and other power-related components. The concern of heat is even more pronounced where LEDs are mounted in a confined space or more than one LED package is used. In such circumstances, it is especially crucial to manage the heat created by the LED module for optimal performance and to protect the overall life of the fixture.
It is known in the art to use a heat-dissipating structure, such as an aluminum plate, for mounting an LED module. This approach has a significant disadvantage in that the plate is generally welded to the housing. Welding of a heat-dissipating structure to the interior of a housing typically causes undesirable distortion of the housing. Alternatively, the heat-dissipating structure may be forced into the housing. This is undesirable because assembling a heat-dissipating structure in this manner typically requires the application of over two tons of force; consequently, the interior of the housing may be significantly damaged during assembly. Further, the application of such tremendous force makes it nearly impossible in the future to remove the heat-dissipating structure for access to the housing.
The relative permanency of traditional heat-dissipating structures within a lighting apparatus housing makes it much more difficult, costly and time-consuming to perform routine maintenance. These problems are only exacerbated in certain lighting fixtures that utilize more than one LED module. For example, in a bollard lighting fixture, it may be desirable in some circumstances to provide two LED modules, one being mounted in the upper portion of a tubular housing and the other in the lower portion of the housing. Where two heat-dissipating plates are welded to the housing, this would significantly impair one's ability to enter the housing for routine maintenance. There is, therefore, a need for lighting apparatus including an LED module where the LED is mounted on a heat-dissipating structure that is easily removable, thereby allowing access to the interior regions of the lighting fixture.